view: Redraw ev-view-presentation when setting normal and black mode.

The black and normal mode are the same from the CSS point of view.
The difference is that in the draw function the page is not drawn
in black mode. Hence, we need to explicitly queue a redraw in these
cases. Since setting the white mode add a CSS class, this queues
the redraw for us.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=772390.